title: Surface-directed molecular assembly of pentacene on monolayer graphene for high-performance organic transistors.
abstract: Organic electronic devices that use graphene electrodes have received considerable attention because graphene is regarded as an ideal candidate electrode material. Transfer and lithographic processes during fabrication of patterned graphene electrodes typically leave polymer residues on the graphene surfaces. However, the impact of these residues on the organic semiconductor growth mechanism on graphene surface has not been reported yet. Here, we demonstrate that polymer residues remaining on graphene surfaces induce a stand-up orientation of pentacene, thereby controlling pentacene growth such that the molecular assembly is optimal for charge transport. Thus, pentacene field-effect transistors (FETs) using source/drain monolayer graphene electrodes with polymer residues show a high field-effect mobility of 1.2 cm(2)/V s. In contrast, epitaxial growth of pentacene having molecular assembly of lying-down structure is facilitated by π-π interaction between pentacene and the clean graphene electrode without polymer residues, which adversely affects lateral charge transport at the interface between electrode and channel. Our studies provide that the obtained high field-effect mobility in pentacene FETs using monolayer graphene electrodes arises from the extrinsic effects of polymer residues as well as the intrinsic characteristics of the highly conductive, ultrathin two-dimensional monolayer graphene electrodes.
authors.affiliation: Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Wi Hyoung
authors.initials: WH
authors.lastname: Lee
authors.forename: Jaesung
authors.initials: J
authors.lastname: Park
authors.forename: Sung Hyun
authors.initials: SH
authors.lastname: Sim
authors.forename: Soojin
authors.initials: S
authors.lastname: Lim
authors.forename: Kwang S
authors.initials: KS
authors.lastname: Kim
authors.forename: Byung Hee
authors.initials: BH
authors.lastname: Hong
authors.forename: Kilwon
authors.initials: K
authors.lastname: Cho
mesh_terms: D004566:Electrodes; D006108:Graphite / Q000737:chemistry*; D008567:Membranes, Artificial; D009279:Naphthacenes / Q000737:chemistry*; D010316:Particle Size; D012666:Semiconductors; D013499:Surface Properties
chemical_list: D008567:Membranes, Artificial; D009279:Naphthacenes; D006108:Graphite; C523499:pentacene